Slider to reduce or increase the size of the rendered image relative to the X/Y values above.
This is useful for small test renders that have the same proportions as the final image.

Aspect Ratio

Older televisions may have non-square pixels,
so this can be used to control the shape of the pixels along the respective axis.
This will pre-distort the images which will look stretched on a computer screen,
but which will display correctly on a TV set.
It is important that you use the correct pixel aspect ratio when rendering to prevent re-scaling,
resulting in lowered image quality.

This panel provides options for setting the location of rendered frames for animations,
and the quality of the saved images.

File Path

Choose the location to save rendered frames.

When rendering an animation,
the frame number is appended at the end of the file name with four padded zeros (e.g. image0001.png).
You can set a custom padding size by adding the appropriate number of # anywhere in the file name
(e.g. image_##_test.png translates to image_01_test.png).

This setting expands Relative Paths
where a // prefix represents the directory of the current blend-file.

Overwrite

Overwrite existing files when rendering.

Placeholders

Create empty placeholder frames while rendering.

File Extensions

Adds the correct file extensions per file type to the output files.

Cache Result

Saves the rendered image and passes to a multi-layer EXR file in temporary location on your hard drive.
This allows the compositor to read these to improve the performance, especially for heavy compositing.

File Format

Choose the file format to save to. Based on which format is used,
other options such as channels, bit depth and compression level are available.

The Post Processing panel is used to control different options used to process your image after rendering.

Post Processing panel.

Sequencer

Renders the output of the Video Sequence editor, instead of the view from the 3D scene’s active camera.
If the sequence contains scene strips, these will also be rendered as part of the pipeline.
If Compositing is also enabled, the Scene strip will be the output of the Compositor.

Compositing

Renders the output from the compositing node setup,
and then pumps all images through the Composite node map,
displaying the image fed to the Composite Output node.

Dithering is a technique for blurring pixels to prevent banding that is seen in areas of
gradients, where stair-stepping appears between colors.
Banding artifacts are more noticeable when gradients are longer, or less steep.
Dithering was developed for graphics with low bit depths,
meaning they had a limited range of possible colors.

Dithering works by taking pixel values and comparing them with a threshold and
neighboring pixels then does calculations to generate the appropriate color.
Dithering creates the perceived effect of a larger color palette by creating a sort of visual color mixing.
For example, if you take a grid and distribute red and yellow pixels evenly across it,
the image would appear to be orange.